public class CompteEntrysLabelProvider extends ObservableMapLabelProvider
		implements IColorProvider {

@Override
	public Color getBackground(Object element) {
	   
           WritableList list = new WritableList() ;
	   list= (WritableList) this.tableViewer.getInput();
	
	   int index = list.indexOf(element);
		
          if ((index % 2) == 0) {
			
			return gray; // color
			
		} else {
			return null;
		}

	
	}



}

public class CompteEntrysLabelProvider extends ObservableMapLabelProvider
		implements IColorProvider {

private boolean isEven = true;

public String getColumnText(Object element, int columnIndex) {

switch (columnIndex) {
	case 0:
		isEven = !isEven; //toggle isEven value each first column

		//get column 3 text
		
	
	case 1:
		//get column 2 text
		
	case 2:
		//get column 3 text
		
	case 3:
        
         default: return "";

}

@Override
 public Color getBackground(Object element) {
	
	//based on IsEven value we alternate the row color	
       if (isEven) {  return gray;} else {return null;	}

	
   }

}